Combustion chamber for gas turbines and having flame tube mounting means allowing radial and axial expansion



Oct. 28, A. BARD COMBUSTION CHAMBER FOR GAS TURBINES AND HAVING FLAMETUBE MOUNTING MEANS ALLOWING RADIAL AND AXIAL EXPANSION Filed March 11,1947 2 SHEETS-SHEET l v d zomlaz'd 2,615,300 ES AND HAVING FLAME' TUBE"MOUNTING MEANS ALLOWING RADIAL AND AXIAL EXPANSION Filed March 11, 19472 SHEETS-SHEET 2 A. A.\LOMBARD COMBUSTION CHAMBER FOR GAS TURBIN w m MMz w m m Patented Oct. 28, 1952 UNITED js'rAr-s S E OFFICE.

COMBUSTION CHAMBER FOB GAS TUR- BINES AND HAVING FLAME TUBE MOUNT- .ING-MEANS ALLOWING 'RADIAL AND AXIAL EXPANSION Adrian Albert Lombard,Clitherce, England, as-

' signor to Rolls Royce Limited, Derby, England,

a British company Application March 11, 1947, Serial No. 733,911 InGreat Britain April 8, 1946 '6 Claims.

This invention relates to combustion chambers of the kind employed inaircraft gas turbine engines. More particularly this invention relatesto combustion chambers of the kind comprising an elongated outer casinghaving an air inlet at one end, and a flame tube mounted within theouter casing. The object of the pres-- '.ent invention is to provideimprovedmeans for .supportingthe flame tubein the outer casing.Accordingto the present invention the flametube in a combustion chamberof the above-kind ,.is supported at each end from the outer casing withfreedom for axial movement and radial ex- "pansion and means is providedfor restraining at :a. single point on the flame tube, relative axial'movement of the'flame tube and the outercasing. Preferably said'memberalso restrains relative "rotational movement of the flame tube. The saidmeans conveniently comprises a spigot and socket carried one by theouter casing and the other by the flame tube.

A specific embodiment of the invention will now be described, by way ofexample, with reference to the accompanying drawings whereof,

Figure 1 is a longitudinal sectional view of a combustion chamberinaccordance withthis invention,

.Figure2'is a view in the direction of arrow 2 A01? Figure 1, and

Figure '3 is. a fragmentary view of a part of- Figure 1 to an enlargedscale for the sake of clar- 1 ity.

'The combustion chamber, as shown in Figure 1, comprises a tubular outercasing 5 having an air inlet 6 at one end and a flame tube I mountedco-axially within the casing 5. The inlet 6 to the combustion chambercommunicates with a compressor of the internal combustion turbine inknown manner. ,The discharge endvof the combustion "chamber is supported"as hereinafter more fully described, from a'nozzle box casing 8 whichalso serves to support the nozzle box 9 by which the combustion productsare conveyed from the chamber to the turbine.

A burner assembly generally indicated by the reference numeral ID ismounted in the inlet end of the casing 5. Fuel is supplied to thisburner from which it emerges as an atomised spray directed towards thedischarge end of the combustion chamber. The air entering the inlet 6 isdivided into various streams, the primary air stream passing betweenvanes H to within the flame tube whilst the secondary air passes betweenthe casing 5 and the flame tube and enters the latter through the holes12. Tertiary radially withinthe outer casing.

a 2 airv flowing between the casing andthe'fla'me tube enters the latterthrough the openings I3.

The burner assembly I0 has a cylin'dricalportion' MLprojecting'into theinlet end of the flame tube 1. 1 The'lattercarries the vanes l I whichim part a swirling motion to the primary air. The

"vanes H carryan inner shroud'liwhich fits on the cylindrical portion Mof the burner'assembly, being slid axially thereon. In this way theflame'tube issu'pporte'd on the burner.

' The outlet end of the flame tube 1' is mounted in the outercasing 5 bymeans'of a-sheet metal band 16' which surrounds the outer surface' ofthe'flame tube and is secured thereto at one end.

The other endof the band I6 is bent outwardly to be clear of the flametube and is provided with a number orslots [1 in a hitherto known manner'to form resilient fingers which 'bear against aring secured to' theendof 'the'outer casing'B. In thisway the flame tube '1 is locatedradially i'n'the outer casingwith-freedom"for axialmovementrelativelythereto. This: mountingalso' permits of theflame tubeexpanding A dowel pin, |8"is screwed 'nto 'a-"c'ollar H! whichissecuredto the outer casing 5 towards the front end of it. :The pinextends across the space between the casing 5 and the'flame tube 1 andfits'as. a spigot in a'soeket 20- secured tothe .flame'tube I. The dowelpin l8 restrai'n's'the flame "tube. from both axial and rotary"movements relativelyto the casing! but imposesno restraint on expansionof the flame tube either radially or axially to each side, of the pin.1"

It will be seen that with the presentinvention the flame tube 1 issupported at ,each..end and is located at a point along its length, thisconstruction'permitting the flame tubeto expand freely both ,zradiallyand axially whilst being correctly located in the outer casing.

I claim:

1. A combustion chamber of the kind employed in an aircraft gas turbineengine comprising an air casing having an inlet end and outlet end, acylindrical member secured to said air casing to lie within it at itsinlet end, a flame tube having an internal cylindrical bore in axialsliding engagement with said cylindrical member, axial sliding means tosupport said flame tube within said air casing at the outlet endthereof, said axial sliding means being of the kind which permits radialexpansion of said flame tube relative to said air casing, and locatingmeans to locate said flame tube axially with respect to the air casing,said locating means permitting free 3 radial expansion of said flametube with respect to said air casing.

2. A combustion chamber of the kind employed in an aircraft gas turbineengine comprising an air casing having an inlet end and an outlet end, acylindrical member secured to said air casing to lie within it at itsinlet end, a flame tube having an internal cylindrical bore in axialsliding engagement with said cylindrical member, axial slidingradially-deformable resilient means to support said flame tube withinsaid air casing at the outlet end thereof, and locating means securedwith respect to said air casing and engaging said flame tube to locatesaid flame tube axially with respect to the air casing, said locatingmeans and said flame tube engaging each other in a manner to permitrelative radial movement therebetween.

3. A combustion chamber of the kind employed in an aircraft gas turbineengine comprising in combination an elongated outer casing having an airinlet at one end and an exhaust" outlet at the other end, an elongatedflame-tube within said outer casing, said flame tube having an inlet endadjacent said air inlet and an outlet end adjacent said exhaust outlet,a cylindrical member secured with respect to said outer casing to liewithin it in said air inlet for supporting said flame tube, a sleeveformed on the inlet end of said flame tube having an internalcylindrical bore to receive said cylindrical member with freedom forrelative axialmovement between said cylindrical member and said flametube at said inlet end, second supporting means secured with respect tosaid outer casing for supporting said flame tube at said outlet end withfreedom for relative axial movement between said second supporting meansand said flame tube at said outlet end, said second supporting meansbeing of the kind which permits radialexpansion of said flame tuberelative to said air casing, and locating means secured with respect tosaid outer casing and engaging said flame tube at a single place betweensaid first andsecond supporting means to prevent axial movement relativeto said outer casing of said I flame tube at said single place.

4; A combustion chamber of the kind employed in an aircraft gas turbineengine comprising an air casing having an inlet and an out- -let end,a-- cylindrical member secured to said air casing to lie coaxiallywithin it at its inlet end, ,aflame tube-having an internal cylindricalbore coaxial vwiththe flame tube and in axial sliding engagement withsaid cylindrical member, axial sliding means to support said flame tubewithin said air casing at the outlet end thereof, said axial slidingmeans being of the kind which permits radial expansion of said flametube relative to said air casing and locating means to locate said flametube axially with end, a cylindrical member secured to said air casingto lie within it at its inlet end, a flame tube, having an internalcylindrical bore in axial sliding engagement with said cylindricalmember, axial sliding means to support said flame tube within said aircasing at the outlet end thereof, said axial sliding means being of thekind which permits radial expansion of said flame tube relative to saidcasing, a radially-inwardly-extending dowel secured to said air casing,and a radially-outwardly-extending socket secured to said flame tube andreceiving said dowel, whereby said dowel and socket locate said flametube axially with respect to said air casing and permit relative radialexpansion between said flame tube and said air casing by sliding of thedowel within the socket.

6. A combustion chamber of the kind employed in an aircraft gas turbineengine comprising an air casing having an inlet end and an outlet end, acylindrical fuel injector secured to said air casing to lie within it atits inlet end, a flame tube having an internal cylindrical bore in axialsliding engagement with said fuel injector, axial sliding means tosupport said flame tube within said air casing at the outlet endthereof, and locating means to locate said flame tube axially withrespect to said air casing, said axial sliding means and said locatingmeans being of the kind which permit radial expansion of said flame tuberelative to said air casing.

ADRIAN ALBERT LOMBARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Date OTHER REFERENCES Proceedings,Institute ofMech. Eng. (London), 1945, vol. 153,,pages 465 and 466.

